1. Field of the Invention
The present invention relates to a solar substrate. More particularly, the present invention relates to a solar substrate with high fracture strength.
2. Description of the Prior Art
Generally, silicon wafers are used as substrates for solar cells in prior art. However, the silicon wafers are brittle materials so that the silicon wafers are fractured easily by external forces in a manufacturing process. Besides for the solar cells, the silicon wafers are usually used for manufacturing semiconductor devices. Additionally, because the demand of the semiconductor devices increases, the demand of silicon material increases correspondingly. Thus, how to avoid the waste of the silicon material (fractured by the external forces) or increase yield of the manufacturing process becomes an important issue. Take the solar cells for example, if the solar cells comprise the substrates with high fracture strength, the possibility of fracturing will be decreased.
Please refer to FIG. 1A and FIG. 1B. FIG. 1A and FIG. 1B illustrate images taken in a process of testing a silicon wafer with high fracture strength in the prior art. The silicon wafers are made by single-crystal silicon substrates. When the silicon wafers are forced by a stress, the stress will concentrate on the local area of the silicon wafers. If the stress is increased gradually, cracks will be produced at the local area of the silicon wafers and the crack propagation becomes obvious. Finally, the silicon wafers are fractured into several pieces (as shown in FIG. 1B).
In prior art, if the silicon wafers are forced by the stress, the stress will concentrate on the local area of the silicon wafers. If the stress can be distributed averagely, the fracture strength of the silicon wafers will be enhanced. To sum up, it is an important issue to develop a solar substrate for solving the said problem.